Covered self-expanding vascular occlusion device

ABSTRACT

A covered self-expanding vascular occlusion device and a method of making and using the device. The device comprises a braided wire member with at least two axially spaced securing members affixed to the braided wire member and a thin film covering at least half of the device. The braided member can be moved between a larger diameter ball-like shape or conical shape in its relaxed position, and a smaller diameter cylindrical shape in its stretched position. The film covering is applied to the device by first stretching a portion of film to form a shape similar to a portion of a device to be covered by the film, then inserting the device into the shape formed in the film so that the film covers at least half of the device, and trimming the film to separate the covered device from the remaining film. The device is used by installing it on the end of a tubular introducer where it is held in its relaxed position until needed. A sliding member inside of the introducer tube then pulls the device into the tube, moving the device to its stretched position as it does so. The sliding member is pulled out of the tube, releasing the device and leaving it inside of the tube and in its stretched condition. The tube is installed in a catheter, and the device pushed from the tube into, through, and out of the catheter where upon exiting the catheter the device then opens to its relaxed condition, lodges in the blood vessel, and immediately and completely occludes the vessel.

CROSS-REFERENCE TO RELATED APPLICATIONS, IF ANY

This application is a division of application Ser. No. 09/314,237, filedMay 18, 1999, now U.S. Pat. No. 6,221,086.

This is a continuation-in-part of U.S. patent application Ser. No.09/042,108, filed Mar. 13, 1998, now U.S. Pat. No. 5,925,060 entitledCovered Self-Expanding Vascular Occlusion Device, pending, and which ishereby incorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A MICROFICHE APPENDIX IF ANY

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates, generally to medical devices. Moreparticularly, the invention relates to vaso-occlusion devices used inradiology and embolotherapy.

2. Background Information

In embolotherapy, it is often desirable to occlude blood flow in asection of vasculature for purposes such as controlling internalbleeding, stopping blood supply to tumors, and relieving vessel-wallpressure in a region of a vessel aneurysm. Numerous devices have beendeveloped for this purpose. U.S. Pat. No. 4,994,069 describes devicesand methods such as cross-linking liquids, cyanoacrylate resins,balloons and helical wire coils. Helical coils found favor, but becausethey are dimensioned to engage the walls of the vessel, they arerelatively stiff and difficult to advance through a catheter.

The device of U.S. Pat. No. 4,994,069 provides a smaller coiled wirethat, when tensioned, would have a linear configuration allowing it toeasily be advanced through a catheter to the desired site. When the wireexits the catheter, it relaxes and takes a random convoluted shape toform a space-filling mass lodged in the vessel at the site of release.However, because the final shape of the relaxed coil in the blood vesselis random, the precise location and specific length the device occupiesin the vessel cannot be guaranteed.

Another problem with wire coils is providing enough occlusion to allow ablood clot to form. A partial solution is to coat the wire with fiberssuch as dacron or cotton, but recanalization can occur by resorption ofthe clot by the bodies fibrinolytic system. The fiber coating alsoincreases the friction between the coated wire and the catheter makingit more difficult to advance the coils through the catheter. Another wayto combine fibers and coiled wire is disclosed in U.S. Pat. No.5,226,911 where flexible fiber loops extend outward from windings of thecoil at regular intervals.

An alternative to helical wire coils is tubular braided devices madefrom radiopaque fibers or wires as disclosed in U.S. Pat. No. 5,423,849.These braided structures are significantly smaller than the vessel intowhich they are to be introduced, so they could easily be pushed througha catheter. The tubular structure could be straight, or convoluted intoa variety of shapes such as a circle, a “C” or a figure “8”. Topically aplurality of devices are introduced at a site in the vasculature. Thebraided wires may have additional fibrous elements attached to them toincrease the occludability of the device.

Another braided structure is disclosed in U.S. patent application Ser.No. 08/608,110, titled Self Expanding Vascular Occlusion Device, filedon Feb. 28, 1996. A braided tubular structure is compressed axially,which expands it diametrically. The structure is then heat-set in thatshape. In one embodiment, the expanded portion is heat-set in the formof a disk. In another embodiment the device has two sections, eachforming a disk which is then shaped into a cone, the final heat-setshape being similar to two cones attached end to end. One of thesedevices is straightened to its cylindrical braided form to advance itthrough a catheter. When it exits the catheter, the device returns toits formed shape and lodges in the blood vessel. Additional fibrousmaterial may be attached inside the core of the device to improve itsoccludability.

Vascular occlusion with all of these devices depends on the flow ofblood being restricted enough by the presence of a large quantity offibrous material in the blood stream. Initial deployment of such devicessignificantly reduces blood flow, but flow may not completely stop it.Clots soon form in the deployed device or devices which further reduceblood flow. Blood flow eventually may be completely stopped by thedevice. This takes time. The effectiveness of such occlusion may also bequite variable. It is desirable

An alternative to helical wire coils is tubular braided devices madefrom radiopaque fibers or wires as disclosed in U.S. Pat. No. 5,423,849.These braided structures are significantly smaller than the vessel intowhich they are to be introduced, so they could easily be pushed througha catheter. The tubular structure could be straight, or convoluted intoa variety of shapes such as a circle, a “C” or a figure “8”. Typically aplurality of devices are introduced at a site in the vasculature. Thebraided wires may have additional fibrous elements attached to them toincrease the occludability of the device.

Another braided structure is disclosed in U.S. patent application Ser.No. 08/608,110, titled Self Expanding Vascular Occlusion Device, filedon Feb. 28, 1996. A braided tubular structure is compressed axially,which expands it diametrically. The structure is then heat-set in thatshape. In one embodiment, the expanded portion is heat-set in the formof a disk. In another embodiment the device has two sections, eachforming a disk which is then shaped into a cone, the final heat-setshape being similar to two cones attached end to end. One of thesedevices is straightened to its cylindrical braided form to advance itthrough a catheter. When it exits the catheter, the device returns toits formed shape and lodges in the blood vessel. Additional fibrousmaterial may be attached inside the core of the device to improve itsoccludability.

Vascular occlusion with all of these devices depends on the flow ofblood being restricted enough by the presence of a large quantity offibrous material in the blood stream. Initial deployment of such devicessignificantly reduces blood flow, but flow may not completely stop.Clots soon form in the deployed device or devices which further reduceblood flow. Blood flow eventually may be completely stopped by thedevice. This takes time. The effectiveness of such occlusion may also bequite variable. It is desirable for a vascular occlusion device to beself-expanding, accurately positionable, and to completely occlude ablood vessel immediately upon deployment.

Despite the need in the art for a vascular occlusion device whichovercomes the disadvantages, shortcomings and limitations of the priorart, none insofar as is known has been developed.

BRIEF SUMMARY OF THE INVENTION

A covered self-expanding vascular occlusion device comprises a braidedwire member with at least two axially spaced securing members affixed tothe braided wire member and a thin film covering at least half of thedevice. Moving the securing members axially relative to each other movesthe braided wire member to shape a portion of the braided wire memberintermediate the first and second securing members. The device ismovable between a first stretched position in which the braided wireportion extends in an essentially cylindrical configuration to a maximumaxial length and a minimum diameter, and a second relaxed position inwhich the axial length of the braided wire portion is reduced and itsdiameter is increased. In the relaxed position, the braided wire portionhas a ball-like shape.

The film covering is applied to the device by first stretching a portionof film to form a shape similar to a portion of a device to be coveredby the film, then inserting the device into the shape formed in the filmso that the film covers at least half of the device, and trimming thefilm to separate the covered device from the remaining film. Stretchingof the film is preferably accomplished by inserting a pin having a tipshaped similar to that of the device into a portion of film held in afixture. The pin is withdrawn from the stretched film, the device ismounted on the end of a mandrel, and inserted into the stretched film.The film is made tight on the device preferably by further stretching ofthe film. After the film is trimmed, the covered device is removed fromthe mandrel.

The device is used by installing it on the end of a tubular introducerwhere it is held in its relaxed position until needed. A sliding memberinside of the introducer tube then pulls the device into the tube,moving the device to its stretched position as it does so. The slidingmember is pulled out of the tube, releasing the device and leaving itinside of the tube and in its stretched condition. The tube is installedin a catheter and the device pushed from the tube into, through, and outof the catheter where upon exiting the catheter the device then opens toits relaxed condition, lodges in the blood vessel, and immediately andcompletely occludes the vessel.

Alternative embodiments of the vascular occlusion device of the presentinvention include features for (1) melting film to wires to prevent filmmigration distally upon implantation, (2) providing holes in film topermit the device to open faster and to remain in place, (3) urinaryincontinence treatment, (4) alternative expanded forms, and (5) filmcreation processes.

Accordingly, it is an object of the present invention to provide aself-expanding vascular occlusion device which can completely occlude ablood vessel immediately upon deployment. The features, benefits andobjects of this invention will become clear to those skilled in the artby reference to the following description, claims and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a ball-like shaped self-expanding vascularocclusion device without a film covering.

FIG. 2 is the device of FIG. 1 with a film covering.

FIG. 3 is a cross sectional partially exploded view of a holding fixturefor stretching film to be applied to a vascular occlusion device.

FIG. 4 is a side view of a pin used to stretch film.

FIG. 5 is a side view showing the pin of FIG. 4 inserted into theholding fixture of FIG. 3 to stretch film.

FIG. 6 is a side view of the holding fixture of FIG. 5 with thestretched film after the pin has been removed.

FIG. 7 is a side view of the vascular occlusion device of FIG. 1attached to the top of a mandrel which is used to insert the device intothe stretched film.

FIG. 8 is a side view of the mandrel of FIG. 7 being inserted into theholding fixture with stretched film of FIG. 6.

FIG. 9 is a side view of the holding fixture and mandrel of FIG. 8showing the mandrel further inserted to stretch the film tight over thevascular occlusion device.

FIG. 10 is a side view of the assembly of FIG. 9 illustrating how thestretched film is cut.

FIG. 11 is a side view of the holding fixture and mandrel showing themandrel and the covered vascular occlusion device being removed from theholding fixture.

FIG. 12 is a side view of the mandrel showing the covered device beingremoved from the mandrel.

FIG. 13 is a side view of a vascular occlusion device and a partiallydisassembled introducer used to introduce the device into a catheter.

FIG. 14 is perspective view of an assembled introducer with a coveredvascular occlusion device installed in it.

FIG. 15 is a side view of a conical shaped self-expanding vascularocclusion device with a film covering.

FIG. 16 is cross sectional view of the device of FIG. 15 installed in ablood vessel.

FIG. 17 is a perspective view of an alternative embodiment of thevascular occlusion device of the present invention.

FIG. 18 is a side view of the vascular occlusion device shown in FIG.17.

FIG. 19 is a perspective view of an alternative embodiment of thevascular occlusion device of the present invention, in an expandedstate, for use in treating urinary incontinence.

FIG. 20 is a perspective view of the vascular occlusion device shown inFIG. 19, in an unexpanded state.

FIG. 21 is a side view of the vascular occlusion device shown in FIG.19.

FIG. 22 is a side view of the vascular occlusion device shown in FIG.20.

FIG. 23 is an illustration of an alternative embodiment of the vascularocclusion device of the present invention.

FIG. 24 illustrates a method of making an alternative embodiment of thevascular occlusion device of the present invention.

FIG. 25 illustrates a method of melting the film at the proximal end ofthe device shown in FIGS. 17 and 18.

DETAILED DESCRIPTION

The present invention is an improvement of the inventor's self-expandingvascular occlusion device disclosed in U.S. patent application Ser. No.08/608,110 (the '110 application), titled Self Expanding VascularOcclusion Device, filed on Feb. 28, 1996. The above patent applicationis hereby incorporated be reference.

Referring to FIGS. 1 and 2, a self-expanding vascular occlusion device40 of the present invention is similar to the devices disclosed in the'110 application in that a ball-shaped structure 20 is formed by firstbraiding a plurality of wires 22 into a tubular structure and capturingthe wires 22 in bands 24 and 26 located at a first end 28 and second end30 of structure 20. As disclosed in the '110 application, bands 24 and26 preferably capture wires 22 between inner band members 31 and 33 andouter band members 35 and 37, the outer band members 35 and 37 beingcrimped, welded, bonded, or otherwise attached to the inner band members31 and 33 when wires 22 are in place. With wires 22 secured to bands 24and 26, bands 24 and 26 are pushed axially toward each other, therebycausing the center of the braided tubular structure to expanddiametrically to form a ball-like shape as shown in FIG. 1. Wires 22 areheat-set in this shape so that structure 20 retains its ball-like shapein when the force pushing bands 24 and 26 toward each other is removed.A smooth hemispherical cap 29 is formed on one end 28, preferably bycapping end 28 with epoxy or other appropriate material.

If bands 24 and 26 were pushed further together, the structure 20 wouldform a single disk-like shape similar to the disk-like shape disclosedin the '110 application. If a single disk shaped device were to cant inthe blood vessel so that the plane of the disk is no longer normal tothe axis of the blood vessel, a significant portion of the edge of thedisk will no longer be in contact with the wall of the blood vessel,thereby allowing leakage past the device. The ball-like shape offers anadvantage over a single disk in that the ball-like shape may cant offthe axis of the blood vessel and the outside of the ball-like shape willremain in contact with the vessel wall.

Wires 22 of the ball-like structure 20 are spaced relatively far apartin the expanded region of the structure, and alone may not provideadequate occlusion. The present invention applies a thin plastic film 32over a major portion of the ball-like structure 20 to make the coveredvascular occlusion device 40 of FIG. 2. Film 32 is stretched to form ashape similar to that of approximately half of the ball-like structure20 as indicated by area 34. The structure 20 is inserted into thepreshaped film and film 32 is further stretched so that film 32 coversend 28 and the film 32 follows the contour of structure 20 over area 34.Film 32 is trimmed to leave a cylindrical skirt section 36 extendingfrom the major diameter of the structure 20 toward end 30. The finalthickness of film 32 can be from five to fifteen micrometers, dependingon the initial film thickness, which is approximately twice that of thefinal thickness. This extremely thin final film thickness is necessaryfor introducing the device through a catheter. When the covered device40 is stretched for introduction through a catheter, the film 32collapses and folds on itself as the diameter of the device 40decreases. If the film 32 were much thicker, the collapsed film wouldtake up too much space which may make the device fit too tightly in thecatheter. When device 40 is deployed in a blood vessel, it opens uponexiting the catheter, thereby expanding the film again and completelyoccluding the vessel immediately upon opening.

Referring to FIGS. 3-12, the preferred method for forming the plasticfilm 32 and installing it onto a ball-shaped self-expanding vascularocclusion device is illustrated. The cross section of a cylindricalholding fixture 50 for stretching the film 32 is illustrated in FIG. 3.The holding fixture comprises a cylindrical body 52 having a bore 54which holds a bushing 56. Bushing 56 guides mandrels used to stretchfilm 32 and install device 20 in the stretched film 32. Flat film 32,preferably low density polyethylene, is sandwiched between two rings 58and 60, which are preferably made of PETG. Rings 58 and 60 trap film 32and hold it taught. Rings 58 and 60 with film 32 are located on top ofbody 52 and secured with cover 62 which attaches to body 52. Cover 62has a large diameter bore which receives rings 58 and 60, and a smalldiameter bore 66 above bore 64 which provides the proper diameter forfilm 32 to be stretched through it.

Referring to FIG. 4, a pin 70 has an upper portion 72 which has an outerdiameter matching that of the outer diameter of the ball-shaped vascularocclusion device 20. End 74 of upper portion 72 is contoured tocorrespond to the contour of device 20. Device 20 is shown superimposedon end 74 of pin 70 to illustrate how the contours align. Lower portion76 has an outer diameter that will allow it to align accurately andslide smoothly in bushing 56.

Referring to FIG. 5, pin 70 is inserted in bushing 56 of holding fixture50 and pushed upward as indicated by arrow A so that upper portion 72 ispushed into film 32 thereby stretching film 32 to the form of upperportion 72. The step could also be accomplished by holding the pin 70stationary and pushing the holding fixture 50 down onto the upperportion 72 of pin 70. It is also possible that the bushing 56 could beeliminated by using accurately indexable machines to hold pin 70 andfilm 32 and bring the two together.

Referring to FIG. 6, once film 32 is stretched, pin 70 is withdrawndownward from holding fixture 50. This process inverts film 32 as pin 70is withdrawn, so pressurized air is blown into holding fixture 50 toreinvert the film back to its stretched form as illustrated.

Referring to FIG. 7, device 20 is mounted on another mandrel 80. Upperportion 82 and lower portion 86 of mandrel 80 have the same outerdiameters as upper portion 72 and lower portion 76 of pin 70. Upperportion 82 has a conical relief 84 to receive device 20. It also has asupport pin 88 which keeps device 20 from compressing when it isinserted into the stretched film 32. End 28 of device 20 has been cappedoff with epoxy or another appropriate technique to form a smoothhemispherical cap. Band 26 of end 30 is installed on support pin 88, andsupport pin slides through inner band 33 and inside device 20 until itcontacts band 24 at end 28. Pin 88 then supports end 28 and device 20during insertion into stretched film 32. Upper portion 82 also has acircumferential cutting groove 90 for trimming stretched film 32 afterdevice 20 has been installed in film 32.

Referring to FIG. 8, mandrel 80 with device 20 attached is slid intoholding fixture 50 in direction of arrow B and device 20 is pushedlinearly into already stretched film 32.

Referring to FIG. 9, after device 20 contacts stretched film 32, mandrel80 is further advanced in the direction of arrow B which furtherstretches film 32 tightly over end 32 of device 20, the exposed surfaceof device 20, and upper portion 82. Insertion of mandrel 80 stops whenfilm 32 has been stretched so that the area in which it is tight againstupper portion 82 extends below cutting groove 90.

Referring to FIG. 10, film 32 is cut circumferentially in cutting groove90 using a razor blade 92 or other suitable cutting technique.

Referring to FIG. 11, mandrel 80 with device 20 now covered with film32, is pushed through holding fire 50 in the direction of arrow C.

Referring to FIG. 12, the completed covered device 40 is then removedfrom mandrel 80 by grasping end 28 of device 40 and pulling it in thedirection of arrow D to slide the covered device 40 off of support pin88.

The preferred material for film 32 is low density polyethylene.Alternatively, film 32 could be made from a bioresorbable material suchas polylactic acid or polyglycolic acid. Film 32 can be surface modifiedto impart a number of characteristics to its surface. Examples of suchcharacteristics are increased lubricity (which may facilitate easierpassage through the catheter), and increased surface energy (which mayfacilitate platelet activation on the surface of the film). Film 32 mayalso have a bioactive surface imparted on it by coating it withsubstances such as prothrombin and fibrinogen, both of which aid inorganized clot formation. Film 32 could also be coated with a radiopaquematerial making device 40 easier to see under radiographic viewing.

In the preferred method described above for making covered device 40,film 32 is held on the device by mechanical interdigitation of film 32and end 28 of the device 20. When the film 32 is wet, it also has anadhesive characteristic which holds it to wires 22. Alternatively, film32 could be glued, welded, or melted onto end 28 to better secure it ondevice 20. Film 32 could also be tack welded over a number of wires 22to secure it to the braided structure of wires 22.

Devices of other configurations such as those disclosed in the '110application may also be covered with a film using the technique setforth above. Some devices may have to be partially stretched wheninstalled in the film to facilitate optimal contact between the deviceand the film.

To use covered device 40, device 40 is installed on an introducer suchas those disclosed in U.S. patent application entitled Introducer for anExpandable Vascular Occlusion Device mailed on MM/DD/98, which is acontinuation in part of U.S. patent application Ser. No. 08/927,535 ofthe same title, mailed Sep. 8, 1997. The above patent application ishereby incorporated by reference. The introducer is used to introducedevice 40 into a catheter for delivery to the intended site in apatient's vasculature.

One embodiment of an introducer 100 suitable for use with covered device40 is illustrated in FIGS. 13 and 14. The introducer 100 comprises anouter tube 102 and an inner member 120 sliding within an axial bore inthe outer tube 102. The inner member 120 holds device 40 in a slottedtubular end of inner member 120, and positions device 40 at an end 114of outer tube 102 and within a cup-shaped transparent shield member 106.

The outer tube 102 has a first end portion 104 on which is attachedshield member 106. Shield member 106 preferably has a shank portion 108with an internal bore which receives end portion 104 of outer tube 102.Shield member 106 also has cup portion 110 extending from shank portion108. Cup portion 110 has an internal bore 112 large enough to receivedevice 40 with generous clearance around device 40. Outer tube 102 has afirst end 114 which opens into bore 112 and preferably does not extendinto bore 112.

Shield member 106 is preferably made of a transparent plastic materialso that device 40 can be readily viewed on introducer 100. Shank portion108 is affixed to outer tube 102 by methods such as gluing or welding,or shank portion 108 may simply have a friction fit on outer tube 102and be pressed on it. Shield member 106 could also be molded directlyonto tube 102, or shield member 106 and tube 102 could be molded as asingle unit. Outer tube 102 may be a metal tube, a plastic tube, or anintegrally molded extension of shank portion 108.

Inner member 120 is preferably a flexible plastic tube made of materialsuch as polyethylene. Inner member 120 has a first end portion 122 oftubular configuration which has an axial slit allowing end 122 to expandradially to receive and grip end 28 of device 40.

Inner member 120 also may have a metal wire 126 disposed inside innermember 120. Metal wire 126 is coextensive with end 124 of inner member120, and has an end 128 which terminates a significant distance from end122 of inner member 120 leaving a portion 130 of inner member 120unreinforced by wire 126. Metal wire 126 provides something solid forinner member 120 to cinch down against should the inner member 120elongate and shrink diametrically under tensile load, thereby reducingrecoil or “snapping” of inner member 120 as it is pulled through outertube 102 to retract device 40 into outer tube 102.

To install a device 40 in the introducer 100 end 124 of inner member 120is inserted into end 114 of outer tube 102 and pushed through outer tube102 until end 124 of inner member 120 extends beyond end 116 of outertube 102 and slit end 122 of inner member 120 extends an inch or sobeyond shield member 106. End 28 of device 40 is installed in the slitend 122 of inner member 120, then end 124 is pulled to slide collet tube120 further through outer tube 102 and pull device 40 inside of cupportion 110 of shield member 106. When the end 122 of inner member 120gripping the device 40 enters the end 114 of outer tube 102, the grip ofthe end 122 of inner member 120 on end 28 of device 40 is tightened bycompressive loading of end 122 of inner member 120. Sliding of innermember 120 is then stopped. End 124 of 120 is then bent to form a hook132 at end 116 of outer tube 102. The hook 132 serves as a handle forgrasping inner member 120 to retract device 40 into outer tube 102, andalso functions to prevent the inner member 120 from sliding back towardthe shield member and releasing device 40.

Device 40 is held by introducer 100 in its relaxed condition outside ofthe outer tube 102 prior to use. To use the device and the introducer;the hook 132 of the inner member 120 is grasped and pulled relative toouter tube 102 which pulls device 40 into outer tube 102 stretchingdevice 40 to its cylindrical shape as it does so. Continued sliding ofthe inner member 120 moves the device 40 along the outer tube 102. Whenthe end 122 of the inner member exits end 116 of the outer tube, theinner member 120 releases the device 40 such that most of the deviceremains in its stretched condition disposed inside the outer tube 102 atend 116. Inner member 120 is discarded and end 116 of outer tube isinstalled in catheter. A push rod or guidewire is then inserted into end114 of outer tube 102 and advanced along tube 102 until it contactsdevice 40. The pushrod or guidewire is used to push the device in itsstretched condition into the catheter and advance it through thecatheter to the desired site of deployment. Shield member 106 provides alarge diameter grasping member used for manually holding the introducerwhile manipulating the pushrod. When device 40 exits the catheter at thesite of deployment, device 40 opens to its relaxed shape and lodges in ablood vessel. The film is pushed up against the vessel wall. Blood flowin that vessel is immediately and completely stopped when device 40opens.

The preferable direction to install a covered vascular occlusion device,such as device 40, is such that the device exits the catheter in thesame direction as the blood flow. In this direction, because end 30 isopen, the arterial pressure wave pushes against the interior of thedevice and the film 32, thereby applying significant radial force to thevessel as it does so. That same arterial pressure also attempts to pushthe device 40 downstream. The force resisting this downstream movementis the frictional force generated by the device 40 pushing against thevessel wall. This frictional force is a function of the coefficient offriction between the film 32 and the vessel wall, the radial force, andthe surface area of contact. The radial force is the total of the radialforce generated by the wires 22 pushing against the vessel wall andsystolic blood pressure pushing against the contact area of the film 32.The greater the contact area, the greater the frictional force.

The above description has all been illustrated using the ball-like shapecovered device 40. Another shape which can be formed from the samestructure as the ball-like shaped device 40 is a conical-shaped device240 illustrated in FIG. 15. Bands 224 and 226, wires 222, andhemispherical cap 229 are the same as those of device 40. To form device240, end 230 is pushed closer to end 228 than in device 40, and wires222 are shaped so that end 230 is invaginated. The device is heat set inis form. Portion 234 of device 240 then has a conical shape. Film 232 isinstalled on the conical shaped device as described above, and skiportion 236 of film 232 is trimmed so that skirt portion 236 extendsbeyond band 226. The conical shaped covered vascular occlusion device240 is very useful for conical shaped vessels or vessels requiring adevice which has greater radial force.

Referring to FIG. 16, if the conical device 240 is installed in a vesselof smaller diameter than its relaxed size, the device 240 cannot open toits original cone form. In that case, the outer portion 238 of wires 222conform to vessel walls 250 over the length L, providing a largercontact area for film 232, which increases the radial force from theinternal pressure due to the blood flow direction.

Referring to FIGS. 17 and 18, an alternative embodiment 300 of thevascular occlusion device is shown. One optional feature of thisembodiment is melting a predetermined region 310 of the film 320 to thenitinol wires near the proximal band 330. This prevents migration of thefilm 320 distally when the device 300 is in an implanted position. FIG.25 illustrates a method of melting the film 320 at the proximal end ofthe device 300. A support pin 360 used for passing the device into thefilm is relatively long. The film 320 is pulled tight around the distaltip of the device. Subsequently, the support 365 and the pin 370 arepushed, at the same time, pushing the device through a guide 375 havingthe same inner diameter as the introducer tube 380. As the device ispushed through the guide 375 there is an axially positioned tube 385,again having the same inner diameter as the introducer tube, on theother side of the guide 375 which keeps the device in its axiallyextended form. Once the proximal end of the device is beneath the regionof the guide contain a heater 390, the heater 390 is turned on. Theheater 390 melts the film 320 to the wires at this point. The excessfilm separates from the film on the device as the material contractsupon heating. The heater 390 is immediately turned off and the film isallowed to cool. Pin 370 is removed from the device, the tube 385 isretracted and the device is either pushed or pulled out of the tube 385.

Referring again to FIGS. 17 and 18, a second optional feature of thisembodiment 300 is to cut, for example by heat, at least one hole 340 inthe proximal side 350 of the device 300. Two or three holes may be cutinstead of one. The hole 340 or holes allow blood to enter the device300. This allows the device to open faster and to remain in place.

Referring to FIGS. 19-22, a further alternative embodiment of thevascular occlusion device is shown. This embodiment has particularutility in incontinence treatment. The device 400 includes tube 410preferably constructed of polyethylene, distal and proximal bands 420 aand b, respectively, a contact pad 430, a guidewire actuator, braiding,preferably constructed of nitinol, and a film disposed over thebraiding, preferably constructed of polyethylene. The guidewire 440disposed down the center of the device 400 and attached to band 420 aand the tube 410 attached to the band 420 b permits the device to beopened and closed for entry and retrieval, via actuation of theguidewire 440, into the urethra of both male and female patients, forexample in the treatment of incontinence.

Referring to FIG. 23, another alternative embodiment of the vascularocclusion device is disclosed having the particular configuration orform shown.

Referring to FIG. 24, yet another alternative embodiment of the vascularocclusion device and an alternative method of making such embodiment,are disclosed. The device embodiment 600 includes a covering 610comprising non-woven polymeric filaments. Such filaments may consist of,though not limited to, polyester or polyurethane. The process ofconstructing the device 600 comprises the step of spraying polymericfilaments 640, for example polyester or polyurethane, directly on to thebraided, preferably nitinol, substructure 620 via one or more sprayheads 630 a and b, respectively, under conditions such that thefilaments 640 stick to the nitinol substructure 620. The substructure620 may be rotated during spraying.

The descriptions above and the accompanying drawings should beinterpreted in the illustrative and not the limited sense. While theinvention has been disclosed in connection with the preferred embodimentor embodiments thereof, it should be understood that there may be otherembodiments which fall within the scope of the invention as defined bythe following claims. Where a claim is expressed as a means or step forperforming a specified function it is intended that such claim beconstrued to cover the corresponding structure, material, or actsdescribed in the specification and equivalents thereof, including bothstructural equivalents and equivalent structures.

What is claimed is:
 1. A method of making a covered vascular occlusiondevice, comprising the steps of: (a) providing the device with a braidedwire member and at least first and second securing members affixed tothe braided wire member at axially spaced locations, the first andsecond securing members being movable axially to shape a portion of thebraided wire member intermediate the first and second securing members,the device being movable between a first stretched position in which thebraided wire portion extends in an essentially cylindrical configurationto a maximum axial length and a minimum diameter, and a second relaxedposition in which the axial length of the braided wire portion isreduced and its diameter is increased; and (b) spray coating polymericfilaments onto the braided wire member, under condition that thepolymeric filaments stick to the braided wire member, for forming a filmcovering at least a portion of the device.
 2. The method according toclaim 1, wherein the polymeric filaments comprise non-woven polymericfilaments.
 3. The method according to claim 1, wherein the polymericfilaments comprise polyurethane filaments.
 4. The method according toclaim 2, wherein the braided wire member comprises nitinol wires.
 5. Themethod according to claim 1, further comprising the step of (b₁)rotating the braided wire member spraying the polymeric filaments.